The proposed work will help fill a major gap in research on contraceptive protection. The U.S. has gone through a contraceptive revolution with the result that high proportions are protected by the pill, IUD and sterilization. Nevertheless, there are substantial proportions using other methods or no method at all, and there is continuing concern about the safety and appropriateness of the more effective methods for many couples. While the literature has documented these massive changes in contraceptive protection, there are few multivariate analyses of the determinants of specific method choice (none using national data). Detailed contraceptive history data from three national fertility surveys are to be analyzed with respect to the correlates of spcecific method usage. This is to be done with statistical procedures that allow the modelling of the multiple possible outcomes of contraceptive choices. Thus we will examine the effects of social variables such as race and education, and of life-cycle variables such as accidental pregnancies and problems with pill use, on the method of contraceptive use and on the persistence of use. Particularly important questions surround the trade-off of method choices, e.g. the extent to which male and female sterilization are substitutes for one another, or the result of differing processes. A wide range of potential determinants (including husband's characteristics) and a number of substantively important outcomes (e.g. nonuse or use of less effective methods) will be explored.